Magnetic transfer is to transfer and record a magnetic pattern which corresponds to an information (for example, a servo signal) carried on a master carrier, onto a slave medium by applying transfer magnetic field in a state that the master carrier carrying the transfer information by means of a fine unevenness pattern of magnetic substance and the slave medium having a magnetic recording part to be subject to magnetic transfer are brought into close contact with each other. For example, such a magnetic transfer method is disclosed in Japanese Unexamined Patent Publication Nos. sho 63-183623, hei 10-40544, hei 10-269566 and etc.
The master carrier used for magnetic transfer is formed by performing a treatment such as photofabrication, sputtering, and etching on a silicon substrate, glass substrate and the like thereby providing an unevenness pattern formed of magnetic substance.
In addition, it is considered to manufacture a master carrier for magnetic transfer by applying the lithography technique used in semiconductor field and the like or the stamper technique used in producing an optical disc stamper.
However, in order to enhance quality of transfer in the magnetic transfer as described in the above, it is required to form a master carrier with a transfer pattern out of a layer of magnetic substance with a good accuracy. In the master carrier, it has been found that the shape of prominence pattern is varied depending on a method of writing the pattern, thereby affecting on the characteristics of transfer.
For example, in a case of rotary type slave medium having disc shape, the unevenness pattern of transfer information corresponding to a servo signal is formed with a prominence pattern in a square or rectangular shape extended in the widthwise direction (radial direction) of track. It has been generally known that this pattern is formed by illuminating laser beam which has been modulated according to an information to be transferred, while rotating a disc coated with an EB resist.
However, if the width of track becomes narrowed to 0.3 μm or less to cope with the increase of recording density and the like, the writing diameter approaches to the limit of writing diameter for a laser beam and it is difficult to form a rectangular pattern because an end portion of prominence pattern is formed into a shape of circular arc. If the end portion of prominence pattern is formed into the shape of circular arc, the circular arc-shaped part causes loss of azimuth in the transfer magnetic field when the magnetic transfer is executed in a state that the master carrier and slave medium are brought into close contact with each other, whereby the magnetic pattern is incompletely formed on the slave medium and it becomes impossible to magnetically transfer and record a signal distinctly.
The present invention was conceived in consideration of the above problems in mind. The object of the present invention is to provide a master carrier for magnetic transfer adapted to enhance signal quality of transfer by reducing loss of azimuth at the time of magnetic transfer even when the width of track has been narrowed.